For OpemJDK/Hotspot there will be a <100ms GC in Java 9: http://openjdk.java.net/jeps/189
Here is how Zing use flags:
-XX:+UseGenPauselessGC - Generational Pauseless GC (GPGC) optimized for minimal pause times.
For OpemJDK/Hotspot there will be a <100ms GC in Java 9: http://openjdk.java.net/jeps/189